Inheritance, variation and evolution(seneca) Flashcards
][The two types of cell division are:
- Mitosis
- Meiosis
Mitosis is used in ———–reproduction.
asexual
Mitosis results in the …
formation of two genetically identical daughter cells.
Meiosis is used in ———- reproduction.
sexual
Meiosis results in the …
formation of four genetically non-identical daughter cells.
The process of reproduction where the nuclei of two gametes (sex cells) fuse to form a …
zygote (a process known as fertilisation)
There are four key features of sexual reproduction:
- Offspring are non-identical
- Cells divide by meiosis
- Male and female gametes fuse
- Two parents
————— are the gametes in animals.
Sperm and egg cells
Sperm and egg cells are the ——– in animals.
gametes
—————— contain the gametes in flowering plants.
Pollen and ovum cells
Pollen and ovum cells contain the ———– in flowering plants.
gametes
What is the name of the cell formed by the fusion of two gametes?
Zygote
Asexual reproduction is the process of reproduction that forms …
genetically identical offspring from only one parent.
Asexual reproduction is common in …
single-celled organisms and some plants.
There are four key features of asexual reproduction:
- No gamete fusion
- Offspring are clones
- Only one parent
- Cells divide by mitosis
The two sets of chromosomes are pulled to opposite ends of the cell. Then, the nucleus divides into …
two.
In sexual reproduction, male and female ——- fuse.
gametes
Gametes contain …
half of the number of chromosomes (containing DNA) found in all body cells.
Each cell has a pair of…
each chromosome (diploid cell).
During sexual reproduction, the male gamete will …
fertilise the female gamete and the fertilised cell now has the normal number of chromosomes (46 in humans).
Once the gametes have combined, the new cell divides by …
mitosis (the cell grows asexually).
As soon as the embryo reaches a certain size, cells begin to …
differentiate (specialise).
Division of cells by meiosis (or meiotic division) in reproductive organs produces gametes with …
half the number of chromosomes found in all other body cells.
Humans can speed up artificial selection through …
selective breeding of plants and animals.
Humans can speed up artificial selection through selective breeding of plants and animals.
This depends on …
genetic variation.
Humans can speed up artificial selection through selective breeding of plants and animals.
This depends on genetic variation.
This process has many benefits, including …
boosting food production and breeding fast horses.
Variation in the offspring increases the chances of a …
population being able to survive environmental change by natural selection.
Variation in the offspring increases the chances of a population being able to survive environmental change by natural selection.This is because …
some individuals are likely to be adapted to the new conditions.
If an organism can reproduce sexually or asexually, it often reproduces asexually when conditions are good. Advantages of asexual reproduction are:
- If conditions are favourable, producing lots of identical offspring is positive.
- Asexual reproduction is faster than sexual reproduction.
- No mate is required. Therefore, asexual reproduction is more efficient with regards to time and energy.
What are the 4 genetically different gametes produced during sexual reproduction called?
haploid cells
The genome is the entire (all) genetic material of an organism. Within a genome, there are lots of levels of organisation:
- DNA
- Genes
- Chromosomes
DNA is a …
double helix polymer, which means it is a polymer (a large molecule made up of many subunits) made up of two strands forming a twisted, ladder shape.
A gene is a —————–. Genes code for a sequence of amino acids, which combine to give a specific protein.
small section of DNA.
A gene is a small section of DNA. Genes code for a …
sequence of amino acids, which combine to give a specific protein
Long strands of DNA are coiled up to form ————-
chromosomes.
Chromosomes contain …
many genes.
Human body cells contain —pairs of chromosomes, one of each pair coming from each parent.
23
Human body cells contain 23 pairs of chromosomes, one of each pair coming from …
each parent.
A gene is a segment of DNA. There are about ——- genes in the smallest human chromosome.
300
The nucleus of eukaryotic cells contains chromosomes made of …
DNA molecules.
Each gene tells how a specific ——— should be made.
protein
In —- , the Human Genome Project was completed. Researchers had successfully studied the entire human genome.
2003
In 2003, the Human Genome Project was completed. Researchers had successfully …
studied the entire human genome.
In 2003, the ————————– was completed. Researchers had successfully studied the entire human genome.
Human Genome Project
In 2003, the Human Genome Project was completed. Researchers had successfully studied the entire human genome. Since then, extensive research has been carried out on it, resulting in a vast increase in our understanding. Potential future implications (effects) of this advance in knowledge include:
- Gene identification
- Human evolutionary and migratory history
- Improving understanding of inherited diseases
Identifying genes linked to different disorders, allowing those at risk to make …
informed lifestyle decisions based on the known risk factors.
DNA is a polymer made up of two long strands of small units that repeat throughout the structure, called …
nucleotides.
Each nucleotides is made up of …
a sugar, a phosphate and a base attached to the sugar.
The two long strands within each DNA molecule are held together by …
attractions between opposite bases.
Each base has one other specific base with which it pairs:
- T pairs with A.
- G pairs with C.
The sugar and phosphates of nucleotides form the …
long strands.
nucleotides are made up of:
- base
- phosphate
- sugar
You can remember the base pairs in DNA (T-A and G-C) by using the phrase …
Tigers Are Great Cats.
Each amino acid is coded for by ————————– (called a codon).
a specific sequence of three bases
Each amino acid is coded for by a specific sequence of three bases (called a ——- ).
codon
The order of the bases on the DNA tells us …
the order for combining amino acids to create particular proteins.
We can change the protein made by a gene by altering the …
sequence of bases in that gene.
The order of bases determines which amino acids are combined to create …
proteins.
The order of bases determines which ————- are combined to create proteins.
amino acids
The process of protein synthesis (creation) happens like this:
- Template taken
- Template used
- Delivery of amino acids
- Unique structure created
In the process of protein synthesis (creation), the template is used to guide protein synthesis on ribosomes located in …
the cytoplasm.
In the process of protein synthesis (creation), specific amino acids are delivered by —————— to the protein chain, where they are added in the order shown on the template.
carrier molecules
In the process of protein synthesis (creation), once complete, the long protein chain …
folds up, giving it a unique structure.
In the process of protein synthesis (creation), a template is taken from the…
DNA and leaves the nucleus.
In the process of protein synthesis (creation), specific amino acids are delivered by carrier molecules to the ———– , where they are added in the order shown on the template.
protein chain
In the process of protein synthesis (creation), specific amino acids are delivered by carrier molecules to the protein chain, where they are …
added in the order shown on the template.
In the process of protein synthesis (creation), once complete, the long protein chain folds up, giving it a unique structure.This unique structure is essential to the protein’s function, in the form of …
enzymes, hormones, or structural proteins (e.g. collagen).
If the order of bases on DNA changes, what happens to the proteins made using the DNA?
the amino acid sequence may change.
A mutation is a …
permanent change in the nucleotide sequence of DNA.
Mutations happen continuously and normally …
only slightly affect proteins or don’t affect them at all
Occasionally, a mutation may change the …
structure or shape of a protein.
—- genetic variants arise from mutations.
All
The outcome of a mutation is almost always detrimental to …
protein function.
The outcome of a mutation is almost always detrimental to protein function.
For example, in enzymes, the 1.
In structural proteins, their 2.
- substrate may no longer be able to bind to the active site.
- strength may be reduced.
Some regions of DNA do not encode …
protein sequences.
Some regions of DNA do not encode protein sequences.
The term given to these sections is …
non-coding DNA.
More rarely, a mutation may give a —————- , such as resistance to an antibiotic in bacteria.
survival advantage
More rarely, a mutation may give a survival advantage, such as resistance to an antibiotic in bacteria.
These mutations can be beneficial and represent the …
foundation of evolution by natural selection.
Alleles are …
different forms of the same gene.
Humans have pairs of every gene and in one gene, each half of the pair may have different …
alleles.
People’s characteristics are determined by the ——- that they have.
alleles
Alleles can either be …
dominant or recessive
A dominant allele is always …
expressed, regardless of the identity of the other allele.
A dominant allele is always expressed, regardless of the identity of the other allele.
It needs 1. to be expressed (2.).
- only one copy present
- BB or Bb
A dominant allele is represented by …
a capital letter, e.g. B.
A recessive allele is only expressed if …
the other allele is also recessive.
It is represented by …
a lowercase letter e.g. b. It needs two copies to be present to be expressed (bb).
Which kind of allele is always expressed?
A dominant allele
Genotype refers to the …
combination of alleles an organism has.
If the two alleles are different, we say that the person is …
heterozygous (Bb).
If the two alleles are the same, we say that the person is …
homozygous (BB or bb).
A phenotype is …
an observed characteristic of an individual.
The phenotype is determined by the …
interaction between the genotype and environment.
Earlobes being attached or free is an example of a ——- , where the alleles present will determine a characteristic, unless the environment interferes.
phenotype
Mutations happen continuously and in most cases, proteins are …
hardly affected, if at all.
Mutations happen continuously and in most cases, proteins are hardly affected, if at all. But occasionally, a mutation may change the —————- of a protein.
structure or shape
Monohybrid inheritance refers to the …
inheritance of traits determined by a single gene.
————————– refers to the inheritance of traits determined by a single gene.
Monohybrid inheritance
Punnett squares are diagrams that help us to …
visualise the outcome of a monohybrid cross.
Punnett Squares are used to calculate the …
ratio of offspring phenotypes.
People can develop disorders if they inherit …
certain alleles.
Cystic fibrosis is caused by a ——— allele.
recessive
Cystic fibrosis is a …
disorder of cell membranes.
Cystic fibrosis causes …
thick, sticky mucus to build-up in the lungs and digestive system.
We can use the knowledge that cystic fibrosis is caused by a recessive allele to work out …
the allele combinations of each individual in a family tree.
If a sufferer of cystic fibrosis has non-suffering parents, what are the parents?
heterozygotes
Polydactyly is a …
disorder where the sufferer has extra fingers or toes.
Polydactyly is caused by a ———– allele.
dominant
Polydactyly is a ————— disorder.
inherited
Family trees can be used to visualise the …
transmission of inherited disorders from one generation to the next.
Embryonic screening is a form of …
genome screening.
We can screen a person’s genome to …
look for genes that may make that person susceptible (vulnerable) to genetic disorders.
The advantages of embryonic screening are:
- IVF embryos
- Prevent suffering
- Financial saving
During IVF, most embryos are …
surplus to requirements anyway.
Although embryonic screening has advantages, it also has disadvantages:
- Discrimination
- Expensive
- Parents become selective
- Ethics
There is the potential that defining the desirability of an embryo based on their genetic make-up could promote …
discrimination.
Healthy human body cells contain 23 pairs of chromosomes, ——— of which is responsible for determining biological sex.
only one
This pair of chromosomes are called the sex chromosomes and can either be …
X or Y
Female biology is XX, so an egg contains …
one X chromosome.
Female biology is —–, so an egg contains one X chromosome.
XX
Males biology is XY, so a sperm contains …
either one X or one Y chromosome.
Males biology is ——, so a sperm contains either one X or one Y chromosome.
XY
How many bases make up a codon when coding for an amino acid?
3
Within a population, variation describes differences in the characteristics of individuals. Variation may be a result of differences in:
- The environment
- Genetics and environment
- Genetics
What term is used to describe the differences in the characteristics of individuals?
Variation
Speciation happens when the …
average phenotypes (observed characteristics) of two populations have diverged (changed) so much that the two populations can no longer breed to produce fertile offspring (offspring that can reproduce).
Evolution is the …
gradual change of inherited characteristics of biological populations over time.
Speciation happens when the average phenotypes (observed characteristics) of two populations have diverged (changed) so much that the two populations can no longer breed to produce fertile offspring (offspring that can reproduce).
——————- species have been formed.
Two different
Speciation can happen as a result of …
evolution
Natural mutations can create …
new alleles and two populations can begin to diverge.
Natural selection was proposed by ————— in 1859.
Charles Darwin
Natural selection was proposed by Charles Darwin in …
1859
Within a biological population, different individuals have …
genetic variation (differences in characteristics).
Individuals possessing genes that make them better adapted to the environment will have a …
greater chance of survival.
Natural selection happens like this:
- Genetic variation
- Survival of the fittest
- Breeding
- Best characteristics survive
Charles Darwin theorised that …
all species evolved from simple life forms that first appeared on Earth more than three billion years ago.
Evolution is the …
gradual change of the inherited characteristics of biological populations over time.
Selective breeding (artificial selection) happens when …
humans choose animals and crops to breed, based on their genetic characteristics.
Many different organisms are used in ——— breeding.
selective
Many different organisms are used in selective breeding. They include …
farm animals and crops.
There are lots of steps for the selective breeding process:
Choose parents who most strongly display the desired characteristic.
Breed the chosen parents.
From the resultant offspring (children), choose the offspring that best display the desired characteristic.
Breed these chosen offspring.
Repeat this process of breeding and re-selection over many generations until all the offspring show the desired characteristic.
What type of selection is selective breeding?
Artificial
—————- are the two most common reasons for a characteristic being considered desirable.
Usefulness and appearance
————— in food crops is a useful characteristic because it improves yield (food production productivity).
Disease resistance
—————— dogs are useful as these animals must co-exist (live with) with humans.
Gentle-natured domestic
In farming, animals that …
produce more milk or meat are also useful for yield-related reasons.
Selective breeding can create some problems:
- Reduced variation
- Inbreeding
Selective breeding can reduce …
variation (differences in characteristics) within a population, making it harder for a species to adapt to environmental change.
Selective breeding can lead to …
inbreeding
Selective breeding can lead to inbreeding. Here, some breeds become …
particularly susceptible to disease or inherited defects.
What agricultural term is used to describe food production productivity?
Yield
Organisms that have been selectively bred for their useful characteristics include:
- dogs
- crops
- farm animals
- flowers
Genetic engineering involves …
modifying (changing) an organism’s genome by introducing a gene from another organism to produce a desired characteristic.
Genetic engineering involves modifying (changing) an organism’s genome by introducing a gene from another organism to produce a desired characteristic. Examples of this are:
- Insulin-producing gene
- Vitamin A rice
The gene that produces insulin can be inserted into …
bacteria
The gene that produces insulin can be inserted into bacteria. Those bacteria can then mass-produce insulin to treat people with …
diabetes
A lack of vitamin A can lead to …
blindness
A lot of communities that were lacking in ———— were found to use rice as the core of their diet.
vitamin A
A lot of communities that were lacking in vitamin A were found to use —— as the core of their diet.
rice
A lot of communities that were lacking in vitamin A were found to use rice as the core of their diet.
Therefore, a …
gene that produced vitamin A was taken from bacteria and added to rice, producing rice (golden rice) that was rich in Vitamin A.
Genetic engineering involves modifying (changing) an organism’s ———- by introducing a gene from another organism to produce a desired characteristic.
genome
Genetic engineering happens like this:
- Cut the gene out
- Cut a vector
- Gene inserted
- Delivering gene
In Genetic engineering, Enzymes are used to …
“cut” a desired gene out of a chromosome.
In Genetic engineering, the same enzyme is used to “cut” a vector. The Vector is …
usually a bacterial plasmid (loop of DNA) or virus.
In Genetic engineering, the vector is used to …
insert the gene into the required cells.
In Genetic engineering, if the gene is delivered into cells before they have differentiated (at the egg or embryo stage), …
all cells in the developed organism will have the gene and show the characteristic.
Other than a plasmid, what else is commonly used as a vector?
Viral Particle
What is the name of the circular ring of bacterial DNA that can be used as a vector in genetic engineering?
Plasmid
Genetic engineering has many different possible applications, including:
- Transferring genes into animals
- Transferring genes into bacteria
- Transferring genes into plants
Sheep have had their genomes modified so that …
their milk contains drugs that can be used to treat human diseases.
Bacterial DNA has been engineered in such a way that it contains the human insulin gene.
By creating a colony of this modified bacteria, there can be …
rapid and cheap production of large quantities of human insulin. This can be used to treat type 1 diabetics.
Many genetically modified (GM) crops exist. They have been engineered to have the following characteristics:
- Resistance to diseases, insects, or herbicides.
- Production of larger or ‘better’ fruits.
Advantages of genetically modified (GM) crops:
- GM crops generally show increased yields.
- They could help to provide the nutrients that are often missing from the diets of those living in developing nations.
For example, golden rice can help reduce vitamin A deficiency, which can cause blindness. - GM crops are popular in some parts of the world and no complications have been experienced so far.
Advantages of genetic engineering:
- Preventing inherited diseases.
- Improving food production efficiency.
Disadvantages of genetically modified (GM) crops:
- Some people expect GM crops to negatively impact wild flower and insect populations, thus reducing biodiversity.
- Some people think that there will be long-term effects of consumption on human health.
- If transplanted genes managed to escape into the natural environment, we could accidentally create a ‘superweed’ that is resistant to herbicides.
Concerns about genetic engineering:
- Because it is a relatively recent development, it is uncertain what the long-term effects may be.
- Some consider it unethical to create new life forms or move genes between species.
What does GM stand for?
Genetically Modified
Clones are …
genetically identical individuals (copies), produced naturally by asexual reproduction.
Animals can be cloned using …
embryo transplants and adult cell cloning.
Plants can be cloned using …
cuttings or tissue culture.
Plants can be cloned in two main ways:
- Cuttings
- Tissue culture
Good parent plants are used by gardeners as a source of …
cuttings
To take a cutting, a branch is cut off from the parent plant. Hormones are then used to …
encourage the roots to grow and the cutting is then planted.
Planting cuttings produce clones of the parent plant.
This allows a …
large number of plants with favourable characteristics to be produced quickly and cheaply.
In plant cloning, Small groups of cells are …
extracted (taken) from a plant and placed in a growth medium (such as a petri dish with plant food in).
In plant cloning, Small groups of cells are extracted (taken) from a plant and …
placed in a growth medium (such as a petri dish with plant food in).
Division of these cells will eventually result in the formation of a clone of the parent plant
The advantages of tissue culture are that it is …
quick, space-efficient and time-independent.
This tissue culture is important for commercial use in …
nurseries and the preservation of rare species.
Developing embryos can be split into smaller groups of cells before differentiation (cell specialisation) to give …
many smaller and identical embryos, which can then be put into host mothers.
To clone animals, we use two primary methods:
- Embryo transplants
- Adult cell cloning
The process of adult cell cloning is:
- Take an unfertilised egg cell and remove the nucleus.
- The egg cell is then injected with the nucleus from an adult body cell, belonging to the animal which is to be cloned.
- An electric shock is given to the egg cell to stimulate it to divide.
- Once the embryo has grown into a larger ball of cells, it is implanted into a surrogate mother.
- The embryo (a clone of the original adult body cell) will continue to develop in the womb of the surrogate.
A farmer fertilised egg cells with sperm from his best bull before splitting the embryo. We call this process:
Embryo transplantation
Developing embryos can be split into smaller groups of cells before ———— to give many smaller and identical embryos, which can then be implanted into host mothers.
differentiation
Developing embryos can be split into smaller groups of cells before differentiation to give many smaller and identical embryos, which can then be implanted into —— mothers.
host
A new species is made when 2 populations have diverged so much that they cannot do what?
Breed
According to Alfred Wallace’s proposal, which of the following is the first stage in speciation?
Geographical isolation
Selective breeders need to ensure that they are not also selecting for ————— traits, like genetic limb defects.
disadvantageous
Charles Darwin’s theory of natural selection proposed that …
all species have evolved from simple life forms that first appeared on Earth more than three billion years ago.
At the time, Darwin’s ideas were met with significant opposition from the scientific community. Some factors that contributed to the slow acceptance of his ideas were:
- Religion
- Inconclusive evidence
- Genes yet to be discovered
Other theories of evolution proposed that changes in an organism over its lifetime could be passed on to its children. The most famous of these theories was ————’s theory of inheritance of acquired characteristics.
Lamarck
Lamarck believed that this newly-acquired characteristic would then be passed on to the next generation.
Lamarck’s theory has since been …
disproven. Changes that happen in an animal’s lifetime are NOT passed on to future generations.
Give an example of the Lamarckian theory of inheritance of acquired characteristics:
An example of this theory is that of the giraffe:
- Giraffes have strikingly long necks, which enable them to reach the upper branches of the acacia trees on which they feed.
- Earlier giraffes had shorter necks and so would have to stretch to reach their food.
- Continual stretching resulted in the elongation of giraffe necks within a lifetime.
- Lamarck believed that this newly-acquired characteristic would then be passed on to the next generation.
Charles Darwin’s theory of natural selection proposed that all species have evolved from simple life forms that first appeared on Earth more than three billion years ago. The process is:
- Genetic variation
- Survival of the fittest
- Successful breeding
- Best characteristics survive
Different individual animals in a population (or species) have —————- combinations of genes (show genetic variation).
different
Individuals that are best adapted to the environment will have a …
greater chance of survival.
Individuals with the best chances of survival are the most likely to ———- successfully (because they survive).
breed
The characteristics responsible for the greater chance of survival are more likely to be …
passed on to the next generation.
Charles Darwin developed his theory of evolution whilst aboard the HMS Beagle on an expedition to the ———————. He built up evidence to support the theory of natural selection and in 1859 he published his ideas in “On the Origin of Species”.
Galapagos Islands
Charles Darwin developed his theory of evolution whilst aboard the —————— on an expedition to the Galapagos Islands. He built up evidence to support the theory of natural selection and in 1859 he published his ideas in “On the Origin of Species”.
HMS Beagle
Charles Darwin developed his theory of evolution whilst aboard the HMS Beagle on an expedition to the Galapagos Islands. He built up evidence to support the theory of natural selection and in 1859 he published his ideas in “———————-“.
On the Origin of Species
Charles Darwin’s theory of natural selection challenged the common belief that …
God was the sole creator of the natural world.
Who came up with the theory of inheritance of acquired characteristics?
Lamarck
Many of the other theories that have been proposed revolve around the concept that changes in an organism over the duration of its life are —————-. The most famous of these theories was Lamarck’s theory of inheritance of acquired characteristics.
heritable
A scientist called Alfred Wallace proposed that new species develop as follows:
- Two populations of the same species become geographically isolated (separated).
- The populations exhibit (show) genetic variation.
- Due to differing environments and selection pressures, natural selection (survival of the fittest) operates differently on the populations.
- This eventually leads to genetic divergence until the populations are unable to interbreed to produce fertile offspring.
- At this point, they have become two different species.
Individuals are members of the same species if they can interbreed (breed amongst themselves) to produce …
fertile offspring
Most people think that Charles Darwin was alone in thinking about natural selection. In fact, ————— wrote to Darwin in 1858, expressing his similar thinking.
Alfred Russel Wallace
Most people think that Charles Darwin was alone in thinking about natural selection. In fact, Alfred Russel Wallace wrote to Darwin in ——-, expressing his similar thinking.
1858
Both Charles Darwin and Alfred Russel Wallace had spent a significant amount of time on …
islands
Both Charles Darwin and Alfred Russel Wallace had spent a significant amount of time on islands. This decision helped their research on evolution because the …
isolation of island populations leads to enhanced speciation rates.
In 1858, Charles Darwin and Alfred Russel Wallace combined their great minds to produce …
joint writings.
After Charles Darwin and Alfred Russel Wallace had produced joint writings, Darwin …
accelerated the publication of ‘On The Origin of Species’ to be the first of the two to publish.
Two populations of the same species that become ———— isolated will begin to diverge, leading to two new species.
geographically
Two populations of the same species that become geographically isolated will begin to ———, leading to two new species.
diverge
Two populations of the same species that become geographically isolated will begin to diverge, leading to …
two new species.
The discovery of genes as a mechanism (way) to inherit characteristics and create variance supported the theory of …
evolution
Fossils show the …
gradual changes in organisms over vast periods of time.
The discovery of genes as a mechanism (way) to inherit characteristics and create variance supported the theory of evolution. In addition to this, the two main sources of evidence are:
- Antibiotic resistant bacteria
- Fossils
Natural selection neatly explains Antibiotic resistant bacteria phenomenon:
- Bacteria reproduce rapidly.
- Mutations occur during reproduction.
- If a mutated bacterium is resistant to antibiotics, it will survive exposure to antibiotics and go on to reproduce.
- This bacterium will represent the original ancestor of a new resistant strain.
The discovery of ———- as the mechanism of inheritance and variation (i.e. that characteristics are passed on to offspring in genes) provides further evidence for the theory of evolution.
genes
There are —- different ways of forming fossils
3
Fossils are found in …
rocks and have been preserved by natural processes.
The hardening of soft materials can produce ———, such as footprints.
casts or impressions
The hardening of soft materials can produce casts or impressions, such as footprints.
For example, …
clay hardens around an organism that is buried within it. This organism then decays, leaving behind a cast of itself.
Hard parts of organisms are gradually replaced by ———– as they decay slowly, creating a rock-like substance.
minerals
Hard parts of organisms are gradually replaced by minerals as they decay slowly, creating a rock-like substance.
When the surrounding sediment turns to rock, the teeth-shaped mineral structure remains …
distinct (different).
Where decomposers cannot —–, preservation is possible.
act
Where ———— cannot act, preservation is possible.
decomposers
Where decomposers cannot act, ———— is possible.
preservation
Decomposers cannot operate in …
glaciers (extreme, low temperatures) and peat bogs (extreme acidity).
There are 3 different ways of forming fossils:
- Preservation when decay is not possible
- Mineral replacement
- Hardening soft materials
Bacteria reproduce rapidly. Mutations occur during reproduction. This means that bacteria can ———- rapidly.
evolve
The development of new antibiotics is a ——————- process.
slow and costly
The development of new antibiotics is a slow and costly process.Antibiotics struggles to …
keep up with the emergence of new strains.
If a mutated bacterial pathogen is resistant to antibiotics, when a person is treated with antibiotics, the bacteria will …
survive and go on to reproduce.
If a mutated bacterial pathogen is resistant to antibiotics, when a person is treated with antibiotics, the bacteria will survive and go on to reproduce.
This bacteria is the …
original ancestor of a new resistant strain.
If a mutated bacterial pathogen is resistant to antibiotics, when a person is treated with antibiotics, the bacteria will survive and go on to reproduce.
This bacteria is the original ancestor of a new resistant strain.
This bacteria will …
spread, as there will be no treatment for it, and people are not immune to it (as they were previously treated with antibiotics).
An example of an antibiotic resistance bacteria is …
MRSA.
Measures must be taken to reduce the emergence of new antibiotic resistance strains:
- Doctors should avoid prescribing antibiotics unnecessarily, for example for treating non-serious or viral infections.
- Patients must finish a course of antibiotics to make sure that all of the bacteria are killed.
- The use of antibiotics in agriculture (for example, cattle feed), should be restricted.
Apart from genes, what are the two main sources of evidence for evolution?
- Fossils
- Antibiotic resistant bacteria
Why can’t decomposers act on many glaciers?
extreme, low temeperatures
Before the mid-19th century, the consensus was that sexual reproduction produced …
offspring that exhibited (had) a blend of characteristics.
Gregor Mendel, an Austrian monk, performed …
breeding experiments on pea plants.
———————–, performed breeding experiments on pea plants.
Gregor Mendel, an Austrian monk
Gregor Mendel, an Austrian monk, performed breeding experiments on pea plants.
This work showed that …
characteristics were determined by inherited “units” passed from parents.
In the late 19th century, the first observastion of how …
chromosomes behave during cell division
In the early 20th century, the similarity between the behaviour of chromosomes and Mendel’s ‘units’ was …
recognised.
In the early 20th century, The similarity between the behaviour of chromosomes and Mendel’s ‘units’ was recognised.
Consequently, it was decided that …
the ‘units’ were located on chromosomes.
In the early 20th century, The similarity between the behaviour of chromosomes and Mendel’s ‘units’ was recognised.
Consequently, it was decided that the ‘units’ were located on chromosomes.
Additionally, the ‘units’ were renamed …
genes.
In the mid-20th century, technological advancements allowed scientists to …
work out the structure of DNA.
Technological advancements allowed scientists to work out the structure of DNA.
—————————————— was also unearthed at this time.
The mechanism by which genes operate
Extinction happens when …
there are no individuals of a species left in the world.
A change in ————- factors can cause an extinction if a species cannot adapt or move to another environment.
abiotic (physical) or biotic (relating to organisms)
Geological and atmospheric changes happening over a longer period of time can also cause …
slower extinctions.
Geological and atmospheric changes happening over a ——— period of time can also cause slower extinctions.
longer
Sometimes abiotic (physical) factors can change rapidly to cause ——
extinctions.
Large volcanic eruptions can change the …
carbon dioxide levels in the atmosphere, block light and cause pH changes in soils.
A meteorite or asteroid impact (like the one —————-) would have a similar (but larger) effect to a large volcanic eruption.
around the time of the dinosaurs
A meteorite or asteroid impact (like the one around the time of the dinosaurs) would have a similar …
(but larger) effect to a large volcanic eruption.
There are different modes of natural selection:
- Stabilising selection
- Directional selection
Stabilising selection is a …
type of natural selection that favours the average phenotype.
Directional selection is a …
type of natural selection that favours an extreme phenotype.
Which type of selection is most likely to take place in environments that don’t change?
Stabilising
Stabilising selection favours the average phenotype (characteristic). An average phenotype is more likely to be beneficial in environments that ….
don’t change.
Directional selection takes place after an environment has experienced …
a change.
what are examples of stabilising selection?
- number of eggs an ostrich lays
- camouflaged fur
- birth weight
give a example of dirtectional selection:
Before the Industrial Revolution, peppered moths were predominantly white. This allowed them to camouflage with the light-coloured trees and lichens in their habitat.
The environment changed when the Industrial Revolution darkened the trees with soot.
The white moths became easier for predators to spot and the white colour was now selected against.
Natural selection caused the frequency of the black-coloured moth to increase because the black colouration became more favourable.
Describe the genetic process of directional selection:
- There is genetic variation in a population (e.g. black and white peppered moths).
- In directional selection, there is a change in environmental conditions that favours an extreme phenotype.
- This means individuals with an extreme phenotype have a selective advantage (e.g. the black peppered moth).
4.Individuals with the extreme phenotype are hence more likely to survive and reproduce. - This will lead to an increase in the extreme allele frequency over time.
Classification groups organisms by comparing their …
similarities and differences
Carl Woese proposed the - domain system. This classifies organisms based on chemical analysis.
3
Carl Woese proposed the 3 domain system. This classifies organisms based on …
chemical analysis.
————- proposed the 3 domain system. This classifies organisms based on chemical analysis.
Carl Woese
Carl Woese proposed the 3 domain system. This classifies organisms based on chemical analysis.
The 3 domains are:
- Archaea - primitive bacteria.
- Bacteria - true bacteria.
- Eukaryota - organisms possessing complex sub-cellular structures (protists, fungi, plants and animals).
Traditional (Linnaean) classification system
The traditional classification system, devised by ————–, categorises organisms based on their structure and characteristics.
Carl Linnaeus
The traditional classification system, devised by Carl Linnaeus, categorises organisms based on …
their structure and characteristics.
The ——————— system, devised by Carl Linnaeus, categorises organisms based on their structure and characteristics.
traditional classification
The traditional classification system, devised by Carl Linnaeus, categorises organisms based on their structure and characteristics.
He created 7 different groups - …
Kingdom, Phylum, Class, Order, Family, Genus, Species.
What anogram do you use for the traditional classification system?
King
Prometheus
Cast
Out
few
gems
souls
Name the domain denoting ‘primitive bacteria’:
Archaea
Name the domain denoting ‘true bacteria’:
Bacteria
what bacteria are called eukaryota?
organisms possessing complex sub-cellular structures (protists, fungi, plants and animals).
Linnaeus classified biodiversity into seven different groups. The diagram shows the groups in …
descending order of size.
Primitive bacteria, many of which are …
extremophiles (i.e. live in extreme environments)
Evolutionary trees are used to …
show how scientists believe organisms are related.
Current classification data is used for…
living organisms and fossil data is used for extinct organisms.
The start of the tree is a ————– and the branches show the species that have evolved from the common ancestor.
common ancestor
The start of the tree is a common ancestor and the branches show the …
species that have evolved from the common ancestor.
What is he bimonial naming system?
In the binomial system of classification, each organism is named for its genus then its species. The system of naming species uses Latin words. Each name has two parts, the genus and the species.
